The research work currently underway aims to learn more about the changes in lymphocyte cell surface markers during the course of various human disease states, including the connective tissue disorders and several disorders where abnormalities in immune mechanisms have been postulated. In addition, attempts will now be made to develop methods of looking at subpopulation of T or B lymphocytes and quantitating changes in their proportions and numbers in parallel with changes in disease activity among several of the connective tissue diseases includang systemic lupus, rheumatoid arthritis, and acute rheumatic fever.